1. Field of the Invention
The present invention relates to a machine and method for removing an old track comprised of old rails and old ties from a ballast bed, and for simultaneously laying a new track comprised of new rails and new ties. The machine comprises a first tie transport apparatus for receiving the old ties, the first tie transport apparatus including a lifting device insertable between the ballast bed and an old tie for engaging the old tie and lifting it off the ballast bed, and a second tie transport apparatus for delivering the new ties and laying the new ties.
2. Description of the Prior Art
A machine of this type has been disclosed in U.S. Pat. No. 5,357,867. This machine may be used in track renewal operations while moving it in one direction to replace an old track by new ties and rails, and in the opposite direction to lay a new track on a prepared ballast bed. During the track renewal operation, the machine is advanced in the one direction while supported on a crawler vehicle on a planar surface section from which the old track has been removed and the ballast has either been removed or planed by a ballast bed planing device preceding the planar surface section in the one direction. The new ties are laid and the new rails are deposited thereon behind the crawler vehicle. The new track is laid while the machine is advanced in the opposite direction, for which purpose the machine must be retrofitted by mounting the crawler vehicle on the machine frame ahead of the transport apparatus for the new ties, with respect to the opposite direction. Furthermore, a lifting device of the transport apparatus for the new ties must be turned around to face the opposite direction. At the same time, the transport apparatus for the old ties and the ballast bed planing device are raised into an inoperative position.
It is the primary object of this invention to provide a machine and method for the renewal of a track, which requires a minimum of retrofitting when the operating direction is reversed.
This and other objects are accomplished in accordance with one aspect of the invention with a machine for removing an old track comprised of old rails and old ties from a ballast bed, and for simultaneously laying a new track comprised of new rails and new ties, which comprises a first tie transport apparatus for receiving the old ties and a second tie transport apparatus for delivering the new ties and laying the new ties. According to the present invention, a lifting device is selectively placeable in an operating position on the first or second tie transport apparatus for insertion between the ballast bed and an old tie for engaging the old tie and lifting it off the ballast bed. This may be done with a coupling device on each tie transport apparatus for detachably affixing the lifting device to the first or the second tie transport apparatus. It is also possible for each tie transport apparatus to include the lifting device, in which case a drive selectively moves each tie lifting device between an operating position for receiving an old tie and an inoperative position.
The operating direction of a machine having the above-described structures may be reversed when a track renewal is effected without any retrofitting. This may be of substantially advantage, for example when a double track is to be renewed. In this case, the machine may be advanced in one direction for removing and laying one rail, and then advanced in the opposite direction on the second track for continuing the renewal work without having to turn around the entire machine in a complicated and time-consuming retrofitting operation. All that is required is to disconnect the lifting device for the old ties from the first tie transport apparatus and to mount it on the second tie transport apparatus, or selectively to move each tie lifting device between an operating position for receiving an old tie and an inoperative position. It is an added advantage that such a machine makes it possible to approach an operating site, where the track is to be renewed, from either direction without having to take the orientation of the machine into consideration.
The track renewal method of the present invention comprises engaging the old ties with a first tie transport apparatus including a tie lifting device for lifting the old ties off the ballast bed and removing the lifted old ties with a first tie conveying device moving in a conveying direction, and simultaneously delivering the new ties to a second tie transport apparatus with a second tie conveying device moving in a conveying direction and laying the new ties on the ballast bed with a second tie transport apparatus. The machine is enabled to reverse the operating direction by detaching the tie lifting device from the first transport apparatus and connecting it with the second tie transport apparatus, and reversing the conveying directions of the first and second tie conveying devices.